Hi All,
(Newbie, so I apologize in advance)
So here is my scenario:
Single subject, 9 total runs (3 with condition A, 3 with condition B, 3 with
condition C) all collected during a single visit.
1st Level Analysis on each run separately.
- 1 EV: Simple 20s block design (rArArArA or rBrBrBrB or rCrCrCrC)
- 1 Contrast: 1
2nd Level Analysis (here is the quandry)
Should I use?
Setup 1 (similar to "tripled" t-test" on website but without additional EV
for removal of means)
EVs:
Input Grp EV1 EV2
A1 1 1 1
A2 1 1 1
A3 1 1 1
B1 1 -1 0
B2 1 -1 0
B3 1 -1 0
C1 1 0 -1
C2 1 0 -1
C3 1 0 -1
Contrasts EV1 EV2
A-C 1 2
C-A -1 -2
A-B 2 1
C-B 1 -1
B-A -2 -1
B-C -1 1
A mean 1 1
B mean -1 0
C mean 0 -1
Or should I use setup 2?
EVs:
Input Grp EV1 EV2 EV3
A1 1 1 0 0
A2 1 1 0 0
A3 1 1 0 0
B1 1 0 1 0
B2 1 0 1 0
B3 1 0 1 0
C1 1 0 0 1
C2 1 0 0 1
C3 1 0 0 1
Contrasts EV1 EV2 EV3
A-C 1 0 -1
C-A -1 0 1
A-B 1 -1 0
C-B 0 -1 1
B-A -1 1 0
B-C 0 1 -1
A mean 1 0 0
B mean 0 1 0
C mean 0 0 1
Or am I missing the boat entirely? I've tried running higher level analysis
with both set-ups and the results come out nearly but not exactly identical
except for the contrasts to determine condition means. Alternatively, should
I run a higher level for each condition separately (single group average)
and then feed those into a third level using one of the above setups but
with only 3 inputs?
Many thanks,
Daniel
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